Question: 2 glue sticks cost $3.64. Which equation would help determine the cost of 15 glue sticks?
Explanation: There are several equations that could help determine the cost, each with a slightly different approach. If we let $x$ represent the cost of 15 glue sticks, we have the following proportion: $\dfrac{x}{15}$ We have to pay $3.64 for 2 glue sticks, and that can be written as a proportion: $\dfrac{\$3.64}{2}$ Since the price per glue stick stays the same, these two proportions are equivalent. $\dfrac{x}{15} = \dfrac{\$3.64}{2}$